About The Mars Rover and How Often Giana Sisters Could be Stored on a Smartphone

When watching the Sol 4 press conference for the Mars Science Laboratory (MSL) mission, better known for the Curiosity rover, the person responsible for the on-board computers was saying that the on-board computer was less powerful than an iPhone. One reporter in the audience was totally baffled by this and asked how it was possible to fly to Mars with something that had less power than the smartphone in his pocket.

A very revealing question as it shows that the general public has no idea of how much processing power is required if no screen is attached to a device and software is highly optimized for a specific purpose. It would probably be even more incomprehensible to him that when flying to the moon, the Apollo Guidance Computer did not run at 1 GHz like his iPhone, but at a mere 2 MHz (500 times slower clock speed), and instead of Gbytes of RAM and flash it contained the equivalent of a meager 4 kbytes of RAM and 64 kbytes of ROM. For the details see here and for the details on the bit level have a look at this excellent book which I just recently finished reading. In other words, the specs are similar to those of a 1980's Commodore 64, even though it's difficult to compare those two computers due to their very different purposes.

But anyway, this made me wonder how many times you could store a C64 game that filled the better part of a 5.25" disc or tape in the days of the C64 on an iPhone with 16 GB of flash today. Let's take the original Giana Sisters game on the C64 for the calculation. The disk image has a size of 174 kbytes to play it in a C64 simulator today. And that's already quite big as the C64 only had 64k of RAM so perhaps it was compressed in some form or shape in memory. But anyway, 174 kbytes it is, more than the ROM of the Apollo Guidance computer could have held only a decade and a half earlier. For the comparison let's take an iPhone with 16 GB of flash, which is roughly 16 000 MB or roughly 16 000 000 kb. The game would fit into the flash memory 91 954 times!

Stunning!

Comments

[dominic]

good point. When resources were scarce, people wrote tight, efficient code. I fear that efficiency is now way down on the list of priorities. But I suppose it's understandable given the complexity of modern software - the priority is to keep it maintainable for bug fixes etc.

Innovation comes from trying to do more than your resources allow!

[disco babu]

I have lost all respect for the iPhone.

[Stefan]

Let's not bash the smart phone CPUs and SW too much. Look at what you can do with an ARM SoC today: 3D games, office work, video, web browsing. At roughly 5 W power consumption. Your average desktop PC burns 20 times as much power for the same job.
So, tailored SoCs and SW indeed do a very efficient job.